1. Field of the Invention
The present invention relates in general to catamaran boats and in particular to pontoon boats wherein the flotation units consist of two elongated water-tight elements of circular cross-section. A pair of external planing fins positioned along the sides of each flotation unit cause the pontoon boat to plane and auxiliary wedge-shaped elements secured to the outboard planing fins provide improved stability while turning the pontoon boat at planing speeds.
2. The Prior Art
A catamaran or pontoon boat normally comprises two separate flotation units bridged by an elevated deck surface which maintains the flotation units in a parallel relationship and spaced a substantial distance apart to provide a vessel having exceptional stability in rough water as a result of its large beam/length ratio. Prior-art pontoon boat flotation units are known which are of a U-shape, circular, octagonal or rectangular cross-sectional configuration. However, the flotation units of most pontoon boats are of a circular cross-section as such flotation units have a low fabrication cost and possess substantial strength without the need for reinforcing structural elements.
Pontoon boats with cylindrical flotation units of U-shaped or circular cross-section have poor planing capabilities as the curvature of the flotation unit area contacting the surface of the water provides extremely small lift throughout a wide range of speeds. If pontoon boats with circular flotation units are propelled at high speeds by use of more powerful motors, the small surface contacting the water cannot maintain the pontoon boat at a constant level and the bow repeatedly rises and falls creating a dangerous control situation.
Another disadvantage of pontoon boats is that the center of gravity of such boats is above the water line and on turns, centrifugal force causes the vessel to bank outwardly. This outward banking increases the downward force on the outboard flotation unit which is furthest from the center of the turn and such flotation unit sinks deeper in the water than normal during a straight course. When turning at higher speeds, greater centrifugal force results and the outboard flotation unit tends to become completely submerged, thereby creating additional drag which generates control problems as well as substantially increasing the turning radius of the vessel.